No vestige of beginning - no prospect of end

In the late C18th James Hutton , farmer and naturalist born in Edinburgh, presented a paper to The Royal Society of Edinburgh arguing that the formation of the Earth was a continuous process over many millennia.Hutton cited as evidence a cliff at nearby Siccar Point, where the juxtaposition of vertical layers of gray shale and overlying horizontal layers of red sandstone could only be explained by the action of stupendous forces over vast periods of time. There Hutton realized that the sediments now represented by the gray shale had, after deposition, been uplifted, tilted, eroded away, and then covered by an ocean, from which the red sandstone was then deposited. The boundary between the two rock types at Siccar Point indicated an evolving world over aeons of time.
I picked up this interesting stone in a car park in Fife and showed it to a friend who has a scientific education and was able to define its significance.
You live and learn - thanks Margaret.